Ok so, I did some tests this week. I never really cooked alot of tenderloin before so I was curious to see it. I cooked it in several different ways:
1. I cut it into cutlets, then flour, egg and crumbs and fried it. It ended up being nice but I think not the best. The issue is with thickness, I think these have to be 1/2 inch thick to get crispy outside and stay tender inside and that's not a cutlet then.
2. I cubed it and fried on highest heat possible for about 5 min until it became golden brown. Took off, added onions garlic and carrots. Cooked until onions became golden brown, added sour cream,. peppercorns, and thyme, brought to simmer, added porn, cooked another 5min. The result was as before. It tasted good and such but meat felt slightly overcooked and kinda underwhelming.
3. I used 3 different bbq sauces and marinaded it for about an hour each, then grilled on high heat for 2 min per side to get char/marks and then finished in oven. Since I was not certain on the temperature and many says it starts from 145f to 155f and then rest period, I cooked each of the 3 to 145, 150, 155f. First bbq sauce was bull's eye,. 2nd was more runnier, spicier, and acidic, and 3rd was spicy korean bbq sauce made form apple and peaches. Once I let all 3 rest, I cut into it and at 145f was still little pink in the middle and I wasn't a fan, at 150f was perfect but it was smallest of the 3 and the one at 155f was best over all. So, I think I like my tenderloin at about 153f + rest.
4. I also did a dry run from 5 different peppercorn spices including white, green, black and all spice berries + salt
5. Same as four except I added orange juice.
4 and 5 were let marinade for about an hour and then same as before, grilled for marks/char and finished in oven to 153f + rest.
Overall, cooking it whole is the best. I think as far as marinade and flavor combo it's up to each person but key is to cook it whole to proper temperature and then let it rest. I also cut mine into about inch thick pieces, since I found it to be the ideal thickness.
This week I am going to try some of the more elaborate stuff like stuffing it and perhaps even grinding it to make some made burgers if I can get a grinder somewhere.
Biggest issue encountered was the cleanup. My bbq grill sits on a stove, so once I got it hot enough, even when oiled (it's new, so It's not seasoned over the years), the bbq mixture would stick like crazy. I let it sit hoping it would unstick, but no
As for sides I have made fried rice, roasted potatoes and just used baguettes to crate a sandwich out of it. All came out nicely.